title: Population expansion and genetic structure in Carcharhinus brevipinna in the southern Indo-Pacific.
abstract: BACKGROUND
  Quantifying genetic diversity and metapopulation structure provides insights into the evolutionary history of a species and helps develop appropriate management strategies. We provide the first assessment of genetic structure in spinner sharks (Carcharhinus brevipinna), a large cosmopolitan carcharhinid, sampled from eastern and northern Australia and South Africa.
  
  
  RESULTS
  Sequencing of the mitochondrial DNA NADH dehydrogenase subunit 4 gene for 430 individuals revealed 37 haplotypes and moderately high haplotype diversity (h = 0.6770 ±0.025). While two metrics of genetic divergence (ΦST and F ST) revealed somewhat different results, subdivision was detected between South Africa and all Australian locations (pairwise ΦST, range 0.02717-0.03508, p values ≤ 0.0013; pairwise F ST South Africa vs New South Wales = 0.04056, p = 0.0008). Evidence for fine-scale genetic structuring was also detected along Australia's east coast (pairwise ΦST = 0.01328, p < 0.015), and between south-eastern and northern locations (pairwise ΦST = 0.00669, p < 0.04).
  
  
  CONCLUSIONS
  The Indian Ocean represents a robust barrier to contemporary gene flow in C. brevipinna between Australia and South Africa. Gene flow also appears restricted along a continuous continental margin in this species, with data tentatively suggesting the delineation of two management units within Australian waters. Further sampling, however, is required for a more robust evaluation of the latter finding. Evidence indicates that all sampled populations were shaped by a substantial demographic expansion event, with the resultant high genetic diversity being cause for optimism when considering conservation of this commercially-targeted species in the southern Indo-Pacific.
authors.affiliation: Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia ; Cronulla Fisheries Research Centre of Excellence, New South Wales Department of Primary Industries, Sydney, New South Wales, Australia.
authors.forename: Pascal T
authors.initials: PT
authors.lastname: Geraghty
authors.forename: Jane E
authors.initials: JE
authors.lastname: Williamson
authors.forename: William G
authors.initials: WG
authors.lastname: Macbeth
authors.forename: Sabine P
authors.initials: SP
authors.lastname: Wintner
authors.forename: Alastair V
authors.initials: AV
authors.lastname: Harry
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Ovenden
authors.forename: Michael R
authors.initials: MR
authors.lastname: Gillings
mesh_terms: D000818:Animals; D001315:Australia; D001483:Base Sequence; D003247:Conservation of Natural Resources / Q000379:methods*; D017931:DNA Primers / Q000235:genetics; D014644:Genetic Variation; D005828:Genetics, Population; D019156:Indian Ocean; D016013:Likelihood Functions; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009245:NADH Dehydrogenase / Q000235:genetics; D010140:Pacific Ocean; D010802:Phylogeny; D011157:Population Dynamics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012754:Sharks / Q000235:genetics*; D013019:South Africa
chemical_list: D017931:DNA Primers; D009245:NADH Dehydrogenase